Cassirer is important in 20th Century philosophy for the attention he gives to the fundamental relationship between myth and language. For Cassirer, myth is a non-subjective form of discourse wherein the origin of language coincides with both the human-divine encounter and the event of being itself. In this article, I trace the disagreement between Cassirer and Heidegger on the nature of the magical (or “primitive”) sign, which is at the heart of mythical discourse. While Heidegger initially argues that this form of sign is structurally impossible on the basis of his accounts of signs and language in Being and Time, he later comes to recognize that he had not properly accounted for its possibility within his phenomenological deduction. I conclude by describing how Heidegger’s notion of poetry eventually comes into alignment with the way Cassirer describes the function of myth and the magical sign.